That familiar "pool smell" might actually be a sign that someone had to go but didn't go to the restroom.

The smell is not chlorine but a by-product that is created when chlorine breaks down urine and fecal matter, AccuWeather reports.

There can be anywhere from 8-20 gallons of urine in a typical pool, according to a study by the University of Alberta. When this urine comes into contact with chlorine, it creates chloramines, which is what's giving off the odor.

When your eyes burn while swimming, that's another sign of trouble. Cyanogen chloride is a chemical created when someone pees in a pool. It's a toxic chemical that causes your eyes to burn.

And in case you needed another reason to make that trip to the bathroom, AccuWeather reports that urine and fecal matter ultimately leaves the pool less clean even if it's broken down. When chlorine in a pool is working to combat urine and fecal matter, there is less of it available to take care of harmful bacteria like e coli.

A good rule of thumb to keep in mind is that if the pool's clean, it won't smell like a pool.